Question: Three faucets fill a 100-gallon tub in 6 minutes.  How long, in seconds, does it take six faucets to fill a 25-gallon tub?  Assume that all faucets dispense water at the same rate.
Since three faucets can fill a 100-gallon tub in 6 minutes, six can do it twice as fast, i.e. 3 minutes.  Additionally, the tub is a quarter the size and thus it will be filled four times as fast which gives $3/4$ minutes or $\boxed{45}$ seconds.